MRI in the Angiography Suite – Can It Guide Treatment Decisions?

Combining intraprocedural MRI with X-ray angiography can help neuroradiologists determine the best course of treatment for patients who have suffered acute ischemic stroke.

Although CT is typically used in the angiography suite, MRI can play a valuable role in helping providers determine if further attempts to recanalize steno-occlusive lesions are valuable or in guiding neuroprotective agent use. In an article published recently in Radiology, investigators from the University of California at San Francisco (UCSF) laid out how integrating MRI with X-ray angiography can lead to better treatment options.

“Our study showed that combined use of angiography and MRI during endovascular acute ischemic stroke intervention is feasible and enabled tissue-based decision making regarding whether or not to proceed with mechanical thrombectomy, place intracranial stents, or administer antithrombotic or blood pressure medications,” said the team led by Steven W. Hetts, M.D., chief of interventional neuroradiology at UCSF Mission Bay Hospitals.

In a retrospective observational study, the team examined patients who received endovascular intervention for acute ischemic stroke between July 2019 and May 2020 who either had angiography with MRI or angiography alone. Of the 47 patients who underwent the stroke intervention, 12 had X-ray angiography with MRI.

According to their findings, MRI directly impacted treatment decision-making in all 12 patients:

Proceeding with mechanical thrombectomy: In two patients, further mechanical thrombectomy was aborted when MRI depicted acute infarct after the initial thrombectomy attempt resulted in incomplete reperfusion. For two additional patients, mechanical thrombectomy was pursued after MRI confirmed salvageable tissues without infarct distal to the persistent arterial occlusion.

Intracranial stent placement: For three patients, MRI contributed to determining whether to place an intracranial stent to treat acutely symptomatic intracranial atherosclerotic disease. One patient had a right M1 MCA for which mechanical thrombectomy showed severe underlying stenosis. Diffusion-weighted imaging showed infarct of the entire penumbra, so no stent was placed because reperfusion would have increased hemorrhage risk. In another patient with small posterior cerebral artery-MCA border zone infarcts visualized on diffusion-weighted imaging, MR angiography identified critical stenosis, and the patient was administered anti-platelet medications and was given a stent in the internal carotid artery stenosis. With the third patient, diffusion-weighted imaging helped differentiate several small new acute infarctions from an older infarction. Mechanical thrombectomy showed underlying high-grade right M1 MCA stenosis. The patient was administered a loading dose of anti-platelet therapy, the MCA underwent angioplasty, and a stent was administered.

Antithrombotic Medication Administration: For the five remaining patients, MRI helped inform the use of antithrombotics in the neurocritical care unit based on the extent of cerebral infarct or hemorrhage. It also helped determine infarct size.

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“Our study showed that combined use of angiography and MRI during endovascular stroke intervention enabled tissue-based decision making to determine whether or not to proceed with mechanical thrombectomy, place intracranial stents, or administer antithrombotic or blood pressure medications,” the team said. “MRI influenced the surgical or medical treatment plan for all patients, which demonstrated the use of the combined use of angiography and MRI.”

Not only can MRI accurately depict core infarct with better contrast-to-noise ratio, but when it is incorporated into the neuroangiography suite, it can also reveal the extent of rapidly evolving tissue infarct.

Recent advancements with portable low-strength MRI machines that can be wheeled into the angiography suite could facilitate this combination with less time and cost investment, they said.

Although including MRI in the angiography suite can provide benefits, integrating it can present challenges, said Massachusetts General Hospital experts Michael H. Lev, M.D. director of emergency radiology and emergency neuroradiology, and Thabele M. Leslie-Mazwi, M.D., director of endovascular stroke services, in an accompanying editorial.

While the average acquisition time with the MRI scanner is, on average, 12 minutes, the transfer time between the angiography unit and the MRI can be substantially longer at 45 minutes. This can present a significant problem with stroke patients where “time is brain.” Mitigating this challenge will require workflow optimization, they said.

But, the prospect of further integrating MRI into the angiography suite is attractive for treating this patient population and others, they said.

“MRI-derived information regarding brain parenchymal tissue status is feasible and may be valuable in making intraprocedural therapeutic decisions for patients with acute stroke in the angiography suite,” they said. “It is not hard to imagine the role of this approach in other neurovascular disease states.”